1. Field of the Invention
The present invention relates to an endoscopic treatment tool which is transendoscopically inserted into a body cavity and is employed in various procedures.
Priority is claimed on Japanese Patent Application No. 2009-066248, filed Mar. 18, 2009, the content of which is incorporated herein by reference.
2. Description of Related Art
Conventionally, endoscopic treatment tools provided with a treatment part such as forceps at the distal end have been known. When conducting treatment on tissue within a body cavity using such an endoscopic treatment tool, it may be necessary to adjust the orientation of a treatment part when the orientation of the treatment part that projects into the body cavity is inappropriate relative to the position of the tissue as a treatment target. When such adjustments are conducted, it is important to cause the treatment part to rotate in precise response to the operations of an operator.
Generally, when rotating a treatment part, an operation part at the proximal end side of the endoscopic treatment tool is rotated. In the case of a treatment tool such as forceps with which opening or closing operations are conducted by pushing or pulling an operating wire or the like that is connected to the treatment part via the operation part, compressive force is exerted in the axial direction of a coil sheath in conjunction with the opening or closing. At such times, compared to a single-strand coil sheath in which a single wire is wound, a multi-strand coil sheath in which multiple wires are wound has higher rotational transmittance, but tends to compress in the axial direction. Consequently, the coil sheath compresses in the axial direction, and the axial force to be transmitted to the distal part decreases, thereby making it impossible to conduct adequate treatment, and rendering procedures more complicated.
In order to solve this problem, the endoscopic treatment tool described in Japanese Unexamined Patent Application, First Publication No. 2008-212620 has been proposed. In this endoscopic treatment tool, a first coil sheath in which a single wire is helically wound is inserted through a second coil sheath in which multiple wires are helically wound in the same direction. The distal end of the second coil sheath is fixed to a movable distal part that serves to conduct treatment, while the proximal end thereof is fixed to an operation part.
In this manner, it is sought to combine compressive resistance and torque transmittance by employing the two types of coil sheath, namely, the first coil sheath and the second coil sheath.